Ethernet is a known type of networking protocol. Ethernet networks are often used for general purpose Internet, LAN and WAN networking. Fibre Channel (FC) is another known networking protocol. Fibre Channel networks are often used for storage networks, such as storage area networks (SANs).
Traditionally Fibre Channel networks are preferred to Ethernet networks for storage applications because of their high throughput and guaranteed delivery of frames. Thus, certain types of computers may be connected to two different networks—a Fibre Channel network for storage access (e.g., access to networked storage devices, such as hard drives RAID arrays, etc.) and an Ethernet network for most other networking functionalities. For example, many existing internet servers include such a dual network configuration.
Converged Enhanced Ethernet (CEE) is a new type of Ethernet networking protocol intended to provide higher throughput and reliability. It has been suggested that a CEE network satisfies the higher requirements for storage networking and can be used to replace existing Fibre Channel networks. However, since much existing storage technology has been designed according to the Fibre Channel protocol, it is considered desirable to have CEE components operate in conjunction with FC components in storage networks instead of completely replacing them. For that purpose the Fibre Channel over Ethernet (FCoE) protocol was developed. FCoE provides for “wrapping” FC frames in Ethernet frames and transmitting them over an Ethernet network (this is also referred to as tunneling of the FC protocol over the Ethernet protocol). While FCoE was originally designed in view of CEE networks it can be used for other types of Ethernet networks.
It is generally considered preferable to at least partially migrate storage networking traffic to CEE networks through the use of FCoE because CEE networks can handle other types of networking traffic as well. Thus, only one network can be used for setups which previously required at least two different types of networks.
FCoE allows for relatively easy transitions between CEE or other Ethernet networks and FC networks. More specifically, a gateway can be placed between an Ethernet network and an FC network (this type of gateway is sometimes referred to as an FCoE gateway). The gateway can wrap FC frames received from the FC network into Ethernet frames according to the FCoE protocol and send the wrapped frames to the Ethernet network. It can also unwrap FCoE Ethernet frames received from the Ethernet network to obtain resulting FC frames which it can send to the FC network. Thus, the gateway can allow an FC and Ethernet networks to be connected to each other. Of course, for the type of gateway discussed above to operate properly, it should receive only FCoE frames from the Ethernet network. If it receives a non-FCoE frame, it cannot convert that frame into a meaningful FC frame.
Various networks (including Ethernet and FC networks) can include different types of networking elements, such as switches, routers, hubs, etc. A switch is a relatively complex element which may include several ports. The switch examines incoming frames and sends them to various ports according to the destination addresses included in the frames. A hub is a relatively simple device. It usually does not examine any addresses within incoming frames. Instead it sends all received incoming frames out to all ports regardless of what their destination address is. The hub relies on other devices on the network to discard frames which are not addressed to them. A switch is considered a “smart” device and a hub a “dumb” device. A switch is usually more efficient than a hub in terms of network utilization because it does not send out unnecessary frames. A hub, however, is usually cheaper and easier to manage.
A network can include a number of switches, hubs and gateways. The large number of networking elements in a network can make the network expensive and difficult to manage. It is therefore considered desirable to reduce the number of networking elements in a network without reducing the network's functionality.